The Adhesive Strength and Degree of Conversion of Remineralizing Hydroxyapatite, Amorphous Calcium Phosphate, and Cerium Oxide Fillers in Experimental Adhesive: A <scp>SEM</scp> and <scp>EDX</scp> Analysis

Remineralizing fillers Amorphous-calcium-phosphate nanoparticles (ACP-NPs), hydroxyapatite (HA-NPs), and cerium dioxide (CeO_2-NPs) on the micro-tensile bond strength (μTBS) and degree of conversion (DC) of the experimental adhesive (EA) to caries-affected dentin (CAD). Forty molars with carious lesions on the occlusal surface extending to the middle third of the dentin were included. The characterization of ACP-NPs, HA-NPs, and CeO₂-NPs was performed using SEM and EDX. CAD samples were arbitrarily assigned to four groups based on the application of remineralizing fillers infused into EA. Group 1, Unmodified EA; Group 2, 5% ACP-NPs in EA; Group 3, 5% HA-NPs in EA; and Group 4, 5% CeO₂-NPs in EA. The composite buildup on the CAD surface was followed by artificial aging. μTBS measurements were evaluated using UTM. The DC of the modified EA was assessed using FTIR spectroscopy. One-way ANOVA and Tukey post hoc tests were used to analyze μTBS and DC. CeO₂-NPs + EA displayed the highest bond integrity scores. The unmodified EA samples exhibited the lowest μTBS values. ACP-NPs + EA and the unmodified adhesive demonstrated comparable bond strength (p > 0.05). DC of samples in Group 2: ACP-NPs + EA (66.11 ± 6.33) was comparable to Group 1 HA-NPs (73.51 ± 4.37) (p > 0.05). The highest DC was observed in Group 1 (Unmodified EA). CeO₂-NPs have the potential to improve bond strength scores when used as a remineralizing filler in EA adhesives. However, the incorporation of NPs at 5% in adhesive reduced the DC.